Semiconductor Lead Layout for Dense Wiring and Wire Bond Strength
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Solution Overview
Problem
In semiconductor devices with dense wiring patterns, the reduced distance between exposed leads results in a decrease in bonding area and strength due to the sealing resin covering, leading to reduced bonding strength between wires and leads.
Innovation Solution
The semiconductor device design includes leads with pad and terminal portions where the terminal portions are exposed outside the sealing resin, allowing for adjustable distance between them without altering the pad and terminal sizes, ensuring consistent bonding area and improved mounting on dense wiring boards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the distance between exposed leads is shortened to accommodate dense wiring patterns, then the adaptability to dense wiring boards is improved, but the bonding area of leads is decreased
Solution Approach 1:
The lead structure is segmented into three distinct portions: a pad portion, a terminal portion, and an intermediate portion connecting them. This segmentation allows the pad portion to maintain its size for adequate bonding area while the terminal portion can be positioned closer to adjacent leads for dense wiring compatibility. The intermediate portion acts as a connector that bridges these requirements.
Solution Approach 2:
The lead structure utilizes three-dimensional spatial arrangement by extending the lead in multiple directions. The pad portion extends in a first direction from the semiconductor element, while the terminal portion extends in a second direction perpendicular to the first direction. This dimensional change allows optimization of bonding area in one dimension while reducing distance to adjacent leads in another dimension.
2Productivity
If the distance between exposed leads is shortened, then the productivity of mounting on dense wiring boards is improved, but the bonding strength is decreased
Solution Approach 1:
The lead is divided into functional segments where the pad portion provides adequate bonding area for wire attachment, ensuring bonding strength, while the terminal portion can be positioned close to adjacent leads for efficient mounting on dense wiring boards. The intermediate portion connects these segments, allowing the structure to achieve both high bonding strength and high mounting productivity.
3Length of stationary object
If the size of covered lead portions is decreased, then the distance between exposed leads is reduced, but the bonding area is reduced
Solution Approach 1:
The lead structure is segmented into a pad portion with adequate size for bonding, a terminal portion for exposure, and an intermediate portion. This segmentation enables the bonding area (pad portion) to be maintained at sufficient size while the distance between terminal portions of adjacent leads is reduced, resolving the contradiction between these two parameters.
Solution Approach 2:
The lead structure transitions from a linear arrangement to a multi-directional configuration. The pad portion extends in a first direction while the terminal portion extends in a second direction perpendicular to the first direction. This dimensional change allows the bonding area to be maintained in one dimension while reducing the distance between terminal portions in another dimension.
Data Source
AI summary
A semiconductor device includes: a semiconductor element including a plurality of electrodes; a first lead including a first pad portion and a first terminal portion; a second lead including a second pad portion and a second terminal portion; a plurality of wires; and a sealing resin. Each of the wires is electrically bonded to one of the plurality of electrodes and to one of the first pad portion and the second pad portion. As viewed in a third direction, a length of a straight line connecting a center of the first pad portion and a center of the second pad portion is defined as a first section length. As viewed in the third direction, a length of a straight line connecting a center of the first terminal portion and a center of the second terminal portion is defined as a second section length. The second section length is different from the first section length.